Thank you very much for your positive and encouraging feedback. We truly appreciate your recognition of our key findings and the structure of our discussion. Please find below our responses to your two comments.

1. If the basic processes that are recorded by isotope ratios are identical not only in individual trees, but also in different local conditions (center of peatland, its edge, bedrock), then why is the variability of radial growth (tree-ring width) not so synchronous? I would like this issue to be given special attention in the discussion.

Thank you for this important comment.

The consistent isotope signals observed across our three differing study sites are supported by a number of previous studies apart from peatlands (Hartl-Meier et al., 2015; Klesse et al. 2018; Saurer et al., 2008; Treydte et al., 2007, 2024 and others) confirming that stable isotopes and their climate signals are generally less dependent on local site conditions compared to tree-ring width (TRW). Thus, this relative independence makes stable isotopes especially valuable in dendroclimatological research across a wide range of environments, including lowlands, where classical tree-ring parameters such as TRW often fail to capture strong climate signals (Cernusak and English, 2015; Hartl-Meier et al., 2015). In contrast, the weaker coherence in radial growth between sites reflects heterogeneous growth patterns driven by differing environmental conditions at the CEN, EDG, and REF sites. These differences - such as peat depth (1.5 m at the edge vs. 5 m in the center), mineral soil over bedrock, water-table depth, rooting conditions, and competition - influence how regional climate signals are translated into wood formation.

As noted in previous studies, peatland environments are characterized not only by high water tables, but also by poor soil aeration, limited nutrient availability, and cold substrates (Kimmel et al., 2010, MacDonald and Yin, 1999). These conditions may lead to the formation of extremely narrow rings (Linderholm et al., 2002), as well as the development of compression wood (Malinen et al., 2005). As a result, developing chronologies that are coherent across ecologically distinct sites - or even among different locations within the same peatland - can be challenging (Smiljanic et al., 2014).

Previous TRW studies that compared Scots pine populations on peat soils (peatland) with those on mineral soils, have shown clear differences in the growth patterns (Edvardsson and Hansson, 2015; Edvardsson et al., 2015). A striking example comes from a comparative study in Lithuania, where TRW chronologies from pine populations growing on adjacent peat and mineral soils - separated by only a few hundred meters - showed no significant correlation (Edvardsson et al., 2015).

In light of the arguments and examples discussed above, we confirm that the impact of local environmental variability on stable isotope ratios is significantly reduced compared to TRW. We will expand the discussion in the manuscript to emphasize that TRW is more susceptible to micro-site hydrological variability, whereas stable isotopes more consistently reflect larger-scale climatic patterns such as temperature and precipitation.

Cernusak, L. A., & English, N. B. (2015). Beyond tree-ring widths: stable isotopes sharpen the focus on climate responses of temperate forest trees. Tree Physiology, 35(1), 1-3.

Edvardsson, J., & Hansson, A. (2015). Multiannual hydrological responses in Scots pine radial growth within raised bogs in southern Sweden. Silva Fennica, 49(4).

Edvardsson, J., Rimkus, E., Corona, C., Šimanauskienė, R., Kažys, J., & Stoffel, M. (2015). Exploring the impact of regional climate and local hydrology on Pinus sylvestris L. growth variability–A comparison between pine populations growing on peat soils and mineral soils in Lithuania. Plant and Soil, 392, 345-356.

Hartl-Meier, C., Zang, C., Büntgen, U. L. F., Esper, J. A. N., Rothe, A., Göttlein, A., ... & Treydte, K. (2015). Uniform climate sensitivity in tree-ring stable isotopes across species and sites in a mid-latitude temperate forest. Tree Physiology, 35(1), 4-15.

Kimmel, K., Kull, A., Salm, J. O., & Mander, Ü. (2010). The status, conservation and sustainable use of Estonian wetlands. Wetlands Ecology and Management, 18, 375-395.

Klesse, S., Weigt, R., Treydte, K., Saurer, M., Schmid, L., Siegwolf, R. T., & Frank, D. C. (2018). Oxygen isotopes in tree rings are less sensitive to changes in tree size and relative canopy position than carbon isotopes. Plant, cell & environment, 41(12), 2899-2914.

Linderholm, H. W., Moberg, A., & Grudd, H. (2002). Peatland pines as climate indicators? A regional comparison of the climatic influence on Scots pine growth in Sweden. Canadian Journal of Forest Research, 32(8), 1400-1410.

Macdonald, S. E., & Yin, F. (1999). Factors influencing size inequality in peatland black spruce and tamarack: evidence from post‐drainage release growth. Journal of Ecology, 87(3), 404-412.

Malinen, J. U. K. K. A., Maltamo, M. A. T. T. I., & Verkasalo, E. R. K. K. I. (2005). Stem and wood properties of Norway spruce on drained peatlands and mineral forest lands in Southern Finland. Baltic Forestry, 11(1), 21-37.

Saurer, M., Cherubini, P., Reynolds‐Henne, C. E., Treydte, K. S., Anderson, W. T., & Siegwolf, R. T. W. (2008). An investigation of the common signal in tree ring stable isotope chronologies at temperate sites. Journal of Geophysical Research: Biogeosciences, 113(G4).

Smiljanić, M., Seo, J. W., Läänelaid, A., van der Maaten-Theunissen, M., Stajić, B., & Wilmking, M. (2014). Peatland pines as a proxy for water table fluctuations: disentangling tree growth, hydrology and possible human influence. Science of the Total Environment, 500, 52-63.

Treydte, K., Frank, D., Esper, J., Andreu, L., Bednarz, Z., Berninger, F., ... & Schleser, G. H. (2007). Signal strength and climate calibration of a European tree‐ring isotope network. Geophysical Research Letters, 34(24).

Treydte, K., Liu, L., Padrón, R. S., Martínez-Sancho, E., Babst, F., Frank, D. C., ... & Loader, N. J. (2024). Recent human-induced atmospheric drying across Europe unprecedented in the last 400 years. Nature Geoscience, 17(1), 58-65.

2. Worship or fear of statistics leads to the fact that in some places the text (primarily the results) resembles cuneiform due to the abundance of numerical data and references to certain statistical estimates. This, of course, distracts from reading the text itself. I understand that these are modern requirements, but many of the presented numbers would be better either summarized in tables or even moved to the supplementary. And in general, excessive enthusiasm for statistics depresses theoretical constructions. The above does not change the good opinion of the work, which deserves to be published.

We appreciate your comment and agree that the Results section could benefit from improved clarity. While the numerical and statistical details are important for supporting our interpretations, we recognize that the current presentation may be overly dense. We will revise the section to better highlight the key findings and enhance readability, with the aim of making the main messages more accessible to the reader.

Thank you very much for your positive and encouraging feedback. We appreciate your support and will carefully address the minor revisions.

Specific comments and recommendations:

1. Please consider showing locations of the meteorological stations and the CRU grid on the map (Fig. 1).

We understand the suggestion to include the locations of the meteorological stations and the CRU grid in Figure 1. However, we would prefer to retain the current version of the map, as it provides a level of detail - particularly in the relief shading - that is important for illustrating the local topography of the three study sites, which are located within just 150-300 meters of each other. Adding the locations of the meteorological stations which are in 30 km distance from the study site, would require significantly expanding the map. Also, presenting the CRU grid (which has a resolution of 0.5° latitude/longitude) would require a broader spatial scale, further compromising the figure’s clarity and focus.

As a compromise, we propose adding a brief statement in the text and figure caption indicating the relative positions of the meteorological stations (i.e., Kroppefjäll to the north and Såtenäs to the northeast of the study site, both ~30 km away, and the closest CRU grid point ~18 km northwest of the study site), to provide geographic context without affecting the visual resolution of the figure.

2. Could the low EPS of the TRW chronology from the EDG site be commented on, please? It is important to ensure the dating accuracy before conducting any further analysis.

Thank you for raising this important point. The dating accuracy of the TRW chronology from the EDG site has been carefully verified through standard statistical and visual cross-dating procedures and we are confident that the dating is robust.

The relatively low EPS likely results from heterogeneous growth patterns among individual trees at this site. During the design of our sampling strategy, we intentionally divided the peatland into EDG and CEN sites to investigate whether the shallower peat depth at the edge (~1.5 m) might form a transitional zone between the central peatland (with peat depths of up to 5 m) and the surrounding mineral soil - potentially affecting tree-growth dynamics. This transitional setting may explain the increased variability in growth responses, leading to lower EPS compared to the other two sites. Additionally, the observed heterogeneity in growth patterns may be linked to periods of compression wood occurrence and/or growth suppression followed by release in some trees, likely in response to localized shifts in hydrological conditions or competition. While no visible signs of disturbance, such as top-kill or scars, were detected, the observed growth patterns suggest that dynamic microsite conditions may have influenced individual tree growth, not consistent across the entire tree population.

In summary, while environmental complexity at the EDG site may contribute to reduced EPS, the chronology remains reliably dated and offers valuable insight into site-specific environmental signals at the peatland edge.



3. Please consider showing temperature and precipitation data over the studied period (maybe as a supplementary figure). It is important since rising temperatures are discussed as a potential reason for decreased d13C (e.g., lines 420-425).

Thank you for this suggestion. We will include plots presenting the temperature and precipitation data that support the interpretation of the δ¹³C trends as a supplementary figure.

4. I find long-term trends in TRW, d13C and d18O slightly overinterpreted. The chronologies cover 60 years, which may be too short to exclude an edge-effect. Moreover, I do not find the TRW chronologies to share a strong similarity (line 385), neither do I agree that long-term trends in d13C "differ remarkably" (line 414). I would recommend moving figures with long-term trends into the supplementary.

Thank you for your comment.

Considering:

“I find long-term trends in TRW, d13C and d18O slightly overinterpreted […]. I would recommend moving figures with long-term trends into the supplementary.”

We agree that referring to “long-term trends” in the context of tree-ring chronologies spanning approximately 60 years may be somewhat exaggerated. We believe, however, that presenting “longer-term trends” -or more accurately, “mid-term trends” - remains valuable, as such patterns are often overlooked in tree-ring studies focused on climate reconstructions. Although our study does not aim to perform a climate reconstruction per se, including low-pass filtered data in the manuscript allows highlighting these broader trends, which are particularly relevant when integrating TRW and/or isotope chronologies from ecologically distinct sites. Therefore, while we propose to retain the concept of longer-term trends in the manuscript, we suggest to simply call it: “low-pass filtered data” or “mid-term trends”, to avoid overinterpretation. We remain convinced that including these trends is important for providing a robust foundation for climate reconstruction and merits discussion in the manuscript.

Considering:

“The chronologies cover 60 years, which may be too short to exclude an edge-effect.”



We are not entirely certain what is meant by “edge-effect” in this context, but we assume the comment may refer to the “age effect” (i.e., juvenile growth-related trends). If that is the case, we would like to kindly clarify a few points.

We acknowledge that a negative trend is visible in TRW series at the CEN site. While this may reflect a juvenile effect in some cases, it is also likely that the presence of compression wood and resulting eccentric growth - common under the unstable and waterlogged conditions typical of peatlands - has contributed to this pattern.

This possibility - that the observed negative trends may be influenced more by compression wood and eccentric growth than by juvenile effects - is further supported by the fact that many of the trees included in the chronologies are older, typically around 80-100 years. Due to sampling limitations, we often did not reach the pith, meaning that the actual age of the trees exceeds the length of the measured series, although we did not apply pith-offset estimations. In some cases, we also excluded innermost rings during measurement or removed them during cross-dating, as they did not cross-date reliably.

Finally, all tree-ring series were detrended under the assumption that non-climatic influences - including potential age-related effects - were effectively removed. We therefore consider the mid-term trends presented in our study to be robust and meaningful.

Considering:

“Moreover, I do not find the TRW chronologies to share a strong similarity (line 385), […] neither do I agree that long-term trends in δ¹³C ‘differ remarkably’ (line 414).”

We agree that the TRW chronologies do not exhibit a strong similarity, but rather a moderate one. Likewise, while the long-term trends in δ¹³C do not differ remarkably, there are some visible discrepancies.

Therefore, we propose replacing the word “strong” with “moderate” in line 385 and adjusting “differ remarkably” to “differ slightly” in line 414.

5. I agree with the Referee#1 that Results are over saturated with numbers and statistics. No doubts they are important, but please consider summarising them to facilitate a smooth understanding of their main message.

We appreciate your and reviewer #1’s comment and agree that the Results section could benefit from improved clarity. While the numerical and statistical details are important for supporting our interpretations, we recognize that the current presentation may be overly dense. We will revise the section to better highlight the key findings and enhance readability, with the aim of making the main messages more accessible to the reader.



6. The d13C values suggest that pines at the reference site are drought stressed (lines 400-405). This finding is independently supported by a positive correlation between TRWs and precipitation (see Fig. 6). The authors may consider mentioning this in the text.

Thank you for this insightful observation, we agree. We will revise the text accordingly to explicitly mention and integrate this supporting evidence.

7. Please consider discussing similarities and differences between the sites: in particular, is the middle site (EDG) closer to the central peatland or to the mineral soil site? Does this relationship change across the tree-ring parameters?

Trees growing in the center (CEN) and at the edge (EDG) of the peatland are situated on slightly elevated, drier hummocks, yet remain rooted in deep organic soils - approximately 1.5 meters deep at the edge, and up to 5 meters in the central areas. Despite these micro-elevations, both sites are generally moist. In contrast, the reference site (REF), situated on bedrock, is covered by a thin layer of mineral soil that retains little moisture, leading to distinctly different hydrological conditions.

In addition to hydrology, the sites also differ in pH and nutrient availability. Trees at the CEN and EDG sites experience lower pH levels and rely solely on nutrients from precipitation. Meanwhile, trees at the REF site benefit from access to both mineral soil nutrients and atmospheric deposition.

We will revise the manuscript to include this additional site-specific information.

8. The interpretation of positive relationship between TRW and d18O at the peatland site (lines 440-450) appears unclear to me and would benefit from re-formulating. In particular, the paragraph starts with stating that higher d18O can be interpreted as drier conditions that in turn, promote tree growth. However, this interpretation is later discarded, and I struggle to understand the reasons.

Thank you for this comment. We will revise the discussion and improve the clarity of this paragraph, here is what we meant:

The observed positive relationship between detrended TRW and raw δ¹⁸O chronologies at the central peatland site initially suggests that slightly lowered water tables and relatively drier surface conditions on hummocks may promote tree growth (e.g., Edvardsson et al., 2016; Smiljanić and Wilmking, 2018). Under such conditions, trees may benefit from improved soil aeration while still accessing sufficient moisture, enabling continued stomatal conductance and carbon uptake even under atmospherically dry conditions (i.e., lower VPD). Importantly, higher δ¹⁸O values do not necessarily indicate soil water limitation or drought stress, but rather enhanced leaf-level evaporative enrichment driven by high atmospheric water demand (i.e., higher VPD). When soil moisture is adequate, stomata may remain open despite high VPD, enabling both continued transpiration and xylem cell production. Therefore, the observed positive relationship between δ¹⁸O and TRW likely reflects conditions where trees experience high evaporative demand but no major constraints on water uptake, supporting both isotopic enrichment and radial growth. The strength of the relationships between TRW, δ¹³C, and δ¹⁸O, however, varies across sites (Fig. 4a, b), ranging from strong to weak or non-significant. This underscores the complex interplay between local hydrology and atmospheric conditions and highlights that wood production in peatland pines cannot be inferred from stomatal behavior alone, but must be understood within site-specific environmental contexts.

Edvardsson, J., Stoffel, M., Corona, C., Bragazza, L., Leuschner, H. H., Charman, D. J., & Helama, S. (2016). Subfossil peatland trees as proxies for Holocene palaeohydrology and palaeoclimate. Earth-Science Reviews, 163, 118-140.

Smiljanić, M., & Wilmking, M. (2018). Drivers of stem radial variation and its pattern in peatland Scots pines: A pilot study. Dendrochronologia, 47, 30-37.

Technical corrections:

1. line 40 - recorder --> recorded

We will correct it accordingly.



2. lines 67-69 need a citation

Citations will be added (e.g.,):

Barbour, M.M., Roden, J.S., Farquhar, G.D. et al. Expressing leaf water and cellulose oxygen isotope ratios as enrichment above source water reveals evidence of a Péclet effect. Oecologia 138, 426–435 (2004).

Roden, J.S., Lin, G. and Ehleringer, J.R., 2000. A mechanistic model for interpretation of hydrogen and oxygen isotope ratios in tree-ring cellulose. Geochimica et Cosmochimica Acta, 64(1), pp.21-35.

3. line 100 lacks a full stop

We will correct it accordingly.

4. line 110 with water pools --> to water pools

We will correct it accordingly.

5. please consider moving the lines 115-120 to the introduction

We agree with the suggestion and will move the content from lines 115-120 to the introduction to improve the contextual framing of the study.

6. line 158 - "similar relationships were observed between isotope chronologies" is unclear in the context of comparing climate parameters

We agree the original sentence was unclear. It will be revised to: “Additionally, isotope chronologies were correlated separately with both gridded and instrumental hydroclimate data, revealing similar relationships in each case (analyses conducted but not shown),” to clarify that two distinct correlation analyses were performed.

7. line 176 - consider explaining what is delta t

The delta T correction refers to an adjustment for systematic temperature differences between stations during the overlapping period, applied because the stations were either relocated or experienced a 10-year downtime. The explanation will be added to the text.

8. line 198 - visual comparison cannot be conducted by calculating correlation coefficients

We will correct it accordingly.

9. The Results section is written in the past tense, whereas usually the past tense is used for Methods only - please consider changing.

Thank you for this observation. While we understand that some disciplines prefer the present tense in the Results section, the past tense is also commonly used in environmental and paleoclimatic research when referring to specific findings derived from analyzed datasets. This usage is well represented in the literature in our field. For the sake of consistency and clarity, we would prefer to retain the past tense in the Results section.

10. lines 217-218 are hard to grasp - please consider reformulating

Following your and reviewer #1’s comments, we will revise the Results section - particularly the statistical descriptions - to improve clarity and better highlight the key findings.

11. Table 1 - please explain Rbar, EPS, and AR1 in the caption

We will revise the caption of Table 1 to include brief explanations of Rbar, EPS, and AR1.

12. Figure 2 - please consider using the same scale for the plots with raw TRW measurements

We appreciate the suggestion. We intentionally used different y-axis scales in the three panels showing raw TRW measurements to accurately represent the growth levels at each site. If we were to apply a uniform scale - based on the widest TRWs from the CEN or EDG sites - the narrower values from the REF site would appear nearly flattened, making it difficult to assess and compare growth rates meaningfully. For this reason, we prefer to retain the site-specific scales. To avoid confusion, we propose adding a short note to the figure caption indicating that the y-axis scales differ between panels.

13. line 316 "temperature whereas" --> "temperature, whereas"

We will correct it accordingly.

14. The section 4.3 refers to the figures 5a and 5b, but it should be 4a and 4b.

We will correct it accordingly.

15. The section 4.2 refers to the figures 6a and 6b, but it should be 5a and 5b.

We will correct it accordingly.

16. line 479 should refer to the Fig. 3 instead of Fig. 2

We will correct it accordingly.

17. lines 482 and 528 Central and Northern Europe --> central and northern Europe

We will correct it accordingly.

18. line 493 - please remove "Obviously"

We will correct it accordingly.